RO water is more convenient because you don't have to treat gallons of tap water from day to day. But, an RO filter needs installation and membrane changes periodically so the initial cost is higher. If you have human safe tap water and can easily treat it to remove the treatment chemicals (using Reptisafe) you can use it to spray your chams. If you have hard or sulphury unfiltered well water like I do the RO filter saves a lot of hassle and time. It was worth every penny.Is it better to use RO water to mist your cham over tap water treated with reptisafe?